Ross Robertson

Sunderland serial killer Mary Ann Cotton is being brought to life in a new TV drama starting on Halloween.

The murderous wife was hanged in 1873 for the murder of her seven-year-old stepson, though it's believed she actually killed many more, including three of her four husbands.

Her biographer David Wilson believes her total victim tally to be 16 or 17.

Now the notorious figure from Sunderland's history is the subject of a new two-part TV drama, where she will be played by Downton Abbey's Joanne Froggatt.

"It's quite a fascinating story, because she's the first recorded female serial killer in Britain that we know of, she said.

"People didn't really think a woman was capable of it. Even when she was imprisoned, there were high-profile people who wrote letters on her behalf saying she can't possibly be capable of it."

Mary Ann Cotton

Dark Angel introduces Mary Ann Cotton when she is 25, and has already suffered the natural loss of four of her children.

The drama paints her as a woman moving around, marrying and creating new families before killing them and taking what money she could.

Froggatt has a theory as to how Mary Ann got away with the killings for so long, and why she lacks notoriety of someone like Jack the Ripper, who terrorised Victorian London.

"I learnt that female serial killers tend to poison or overdose or smother people, clean and tidy ways," said the actress.

Joanne Froggatt as Mary Ann and Alun Armstrong as George Stott.

"Men like to make a mess and it's often a sexually driven crime. For women, it's more to move up, in either social or financial status."

She added: "Had she stayed in one place, people may have become suspicious that all these people around her had died."

Dark Angel also stars Alun Armstrong as her step father, George Stott

Froggatt, 36, who has appeared in TV series Bad Girls, Life On Mars and See No Evil: The Moors Murders, said she was looking forward to playing the killer after portraying the compassionate lady's maid Anna Bates in Downton for so long.

Joanne Froggatt

As the massively popular period drama neared its conclusion, she was often asked what role she would like to play next.

"I jokingly said a murderer," said the actress. "And then the script for Dark Angel came through."

"(Mary Ann Cotton) was from the North East and I'm from Whitby, which isn't that far away, and I hadn't heard of her," said Froggatt, who is looking forward to telling the murderer's little-known story.

"She's a working class woman in the Victorian era and there's no opportunity, no choice. She was more or less constantly pregnant.

"It's a monotonous hell and she always felt that it was a life that wasn't right. She always wanted more than that."

l Dark Angel is a two-part drama beginning on ITV on Monday, October 31 at 9m. It concludes on November 7